Boiler tubes that extend between upper and lower drums of a two drum boiler are subject to varying degrees of tube vibration that may do physical harm to the integrity of the apparatus. This vibration is especially noticeable above about 1500.degree. F. where tube vibration is commonly attributed to impingement with a jet of steam given off by the sootblowers, to vortex shedding, jet switching in combination with less than adequate damping characteristics of the boiler tubes, or it has been attributed to some other flow phenomena that cause flow vortices around the tubes.
The present state of the art is such with gas flow induced vibrations that it is impossible to establish an accurate correlation between gas flow, tube damping, and vibration type failures. Corrective measures have in most cases required the installation of physical restraints that snub the vibration whenever such restraints were deemed necessary.
A standard physical restraint has been developed that is simply connected to the tubes to dampen their vibration, but no change in the basic design of the tube banks has been effected. However, excess vibration occurs only occasionally, so it is not deemed economically expedient to incorporate an expensive vibration restraint into all units before the necessity of such a preventative measure should become evident.